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Auteur Anton Beljaars |
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Affiner la recherche Interroger des sources externesOperational meteorology in West Africa : observational networks, weather analysis and forecasting / Andreas H. Fink in Atmospheric Science Letters, vol 12 n° 1 (January - March 2011)
Titre : Operational meteorology in West Africa : observational networks, weather analysis and forecasting Type de document : Article/Communication Auteurs : Andreas H. Fink, Auteur ; Anna Agustí‐Panareda, Auteur ; Douglas J. Parker, Auteur ; Jean-Philippe Lafore, Auteur ; Jean-Blaise Ngamini, Auteur ; Ernest Afiesimama, Auteur ; Anton Beljaars, Auteur ; Olivier Bock Année de publication : 2011 Projets : AMMA & AMMA-2 / Janicot, Serge Article en page(s) : pp 135 - 141 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Afrique occidentale
[Termes IGN] coordonnées GPS
[Termes IGN] données météorologiques
[Termes IGN] modèle météorologique
[Termes IGN] mousson
[Termes IGN] prévision météorologique
[Termes IGN] radiosondage
[Termes IGN] teneur intégrée en vapeur d'eauRésumé : (Auteur) Real‐time surface and upper‐air observations are crucial to the analysis and forecasting of the West African monsoon (WAM). This paper will focus on the African Monsoon—Multidisciplinary Analyses (AMMA)‐driven reactivation and modernisation of the radiosonde network over West Africa, its potential long‐term impact on upper‐air operations in the region, the influence of the additional data in WAM analyses and forecasting, and the AMMA‐related development and usage of the West African Analysis/Forecasting (WASA/F) forecast method. Numéro de notice : A2011-594 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/asl.324 Date de publication en ligne : 22/02/2011 En ligne : https://doi.org/10.1002/asl.324 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91518
in Atmospheric Science Letters > vol 12 n° 1 (January - March 2011) . - pp 135 - 141[article]
Titre : The large‐scale water cycle of the West African monsoon Type de document : Article/Communication Auteurs : Olivier Bock Année de publication : 2011 Projets : AMMA & AMMA-2 / Janicot, Serge Article en page(s) : pp 51 - 57 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Afrique occidentale
[Termes IGN] analyse comparative
[Termes IGN] analyse diachronique
[Termes IGN] bilan hydrique
[Termes IGN] coordonnées GPS
[Termes IGN] données météorologiques
[Termes IGN] modèle météorologique
[Termes IGN] mousson
[Termes IGN] vapeur d'eau
[Termes IGN] variation saisonnièreRésumé : (Auteur) The vertically integrated water budget of West Africa is investigated with a hybrid dataset based on observational and modelling products elaborated by the African Monsoon Multidisciplinary Analyses (AMMA) and with several numerical weather prediction (NWP) products including the European Centre for Medium‐Range Weather Forecasts (ECMWF) AMMA reanalysis. Seasonal and intraseasonal variations are quantified over the period 2002–2007. Links between the budget terms are analyzed regionally, from the Guinean coast to the Sahel zone. Water budgets from the NWP systems are intercompared and evaluated against the hybrid dataset. Large deficiencies are evidenced in all the NWP products. Hypotheses are proposed about their origins and several improvements are foreseen. Copyright © 2010 Royal Meteorological Society. Numéro de notice : A2011-593 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/asl.288 Date de publication en ligne : 16/08/2010 En ligne : https://doi.org/10.1002/asl.288 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91516
in Atmospheric Science Letters > vol 12 n° 1 (January - March 2011) . - pp 51 - 57[article]
Titre : West African Monsoon water cycle: 2. Assessment of numerical weather prediction water budgets Type de document : Article/Communication Auteurs : Rémi Meynadier, Auteur ; Olivier Bock Année de publication : 2010 Article en page(s) : 24 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Afrique occidentale
[Termes IGN] circulation atmosphérique
[Termes IGN] coordonnées GPS
[Termes IGN] données météorologiques
[Termes IGN] évapotranspiration
[Termes IGN] mousson
[Termes IGN] prévision météorologiqueRésumé : (auteur) Water budgets from European Centre for Medium‐Range Weather Forecasts (ECMWF) Re‐Analysis (ERA)‐Interim and National Centers for Environmental Prediction (NCEP) Reanalysis I and II are intercompared and compared to GPS precipitable water and to the 6 year hybrid budget data set described in part 1 of this study. Deficiencies are evidenced in the reanalyses which are most pronounced over the Sahel. Results from operational models (ECMWF Integrated Forecast System, NCEP Global Forecast System, and ARPEGE‐Tropiques) and the special ECMWF African Monsoon Multidisciplinary Analyses reanalysis confirm and help understanding these findings. A bias (∼1–2 mm d−1) in precipitation and evapotranspiration leads to an unrealistic view of West Africa as a moisture source during the summer. North of the rainband (13°N–16°N), moisture flux convergence (MFC) shows a minimum in the NCEP models and divergence in the ECMWF models not consistent with the hybrid data set. This feature, added to presence of a deep layer of northerly dry air advected at midlevels (800–400 hPa), is thought to block the development of deep convection in the models and the northward propagation of the monsoonal rainband. The northerly flow is part of a shallow meridional circulation that is driven by the Saharan heat low. This circulation appears too strong in some of the models, a possible consequence of the too‐approximate representation of physical processes and land surface properties over the Sahel. In most of the models, evapotranspiration shows poor connection with precipitation. This is linked with large analysis increments in precipitable water, soil moisture, and MFC. Despite the large biases affecting the water budget components in the models, temporal variations (seasonal and interannual) might nevertheless be recovered with reasonable accuracy. Numéro de notice : A2010-654 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/2010JD013919 En ligne : https://doi.org/10.1029/2010JD013919 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91725
in Journal of geophysical research : Atmospheres > vol 115 n° D19 (2010) . - 24 p.[article]Documents numériques
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West African Monsoon water cycle 2 - pdf éditeurAdobe Acrobat PDF
Titre : Radiosonde humidity bias correction over the West African region for the special AMMA reanalysis at ECMWF Type de document : Article/Communication Auteurs : Anna Agustí‐Panareda, Auteur ; Drasko Vasiljevic, Auteur ; Anton Beljaars, Auteur ; Olivier Bock Année de publication : 2009 Projets : AMMA & AMMA-2 / Janicot, Serge Article en page(s) : pp 595 - 617 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Afrique (géographie physique)
[Termes IGN] erreur systématique
[Termes IGN] mousson
[Termes IGN] radiosondage
[Termes IGN] teneur en vapeur d'eauRésumé : (auteur) During the African Monsoon Multidisciplinary Analysis (AMMA) field experiment in 2006 there was a large increase in the number of radiosonde data over West Africa. This has the potential of improving the numerical weather prediction (NWP) analysis/forecast and the water budget studies over that region. However, it is well known that the humidity from radiosondes can have some errors depending on sonde type, relative humidity (RH), temperature and the age of the sensor and can give rise to dry biases that are typically between 5% and 30% for RH. Three main sonde types were used in the AMMA field experiment: Vaisala RS80A, Vaisala RS92 and MODEM. In this article, a new empirical method is presented by using the operational European Centre for Medium‐Range Weather Forecasts (ECMWF) short‐range forecast as an intermediary dataset for computing biases. The validation of the correction method using global positioning system (GPS) total columnar water vapour (TCWV) confirms that the method is able to correct for a large part of the dry biases associated with the different sonde types. Results from analysis experiments show how the correction of humidity is particularly important in the West African region due to its impact on the development of convection in NWP models. The proposed radiosonde humidity bias correction has been applied to the special AMMA reanalysis experiment performed at ECMWF for the 2006 West African wet monsoon season. This is expected to benefit a wide number of AMMA‐related studies that make use of the reanalysis, in particular those focusing on the water cycle. Numéro de notice : A2009-574 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/qj.396 Date de publication en ligne : 23/03/2009 En ligne : https://doi.org/10.1002/qj.396 Format de la ressource électronique : URL bulletin Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96190
in Quarterly Journal of the Royal Meteorological Society > vol 135 n° 640 (April 2009 part A) . - pp 595 - 617[article]
